HSG282: The HSE Guide to Spa Pool Safety for UK Operators and Engineers

If you service hot tubs, hotel spa pools, holiday park Jacuzzis, or any spa-type water feature used by the public or paying guests, HSE HSG282 is the guidance document you are working to. Understanding it — and being able to explain it to clients — is core competence for commercial spa pool work.

This guide explains what HSG282 covers, who it applies to, what the key practical requirements are, and how it interacts with other legislation.

What Is HSG282?

HSG282 is the Health and Safety Executive's guidance document titled Control of legionella and other infectious agents in spa-pool systems. It was published in January 2017 (printed 2018).

The HSE describes its scope directly: the guidance applies to "domestic-type spa pools or hot tubs used as part of a business activity, for example in holiday-park rental units, hotel bedrooms with a dedicated spa." The primary infectious risk addressed is Legionella pneumophila — the organism responsible for Legionnaires' disease — alongside other infectious agents as referenced in the document title.

HSG282 addresses Legionella as its primary focus, given the severity of Legionnaires' disease (a form of pneumonia with significant mortality, particularly in elderly and immunocompromised individuals) and because hot tub conditions — warm aerated water — are ideal for Legionella proliferation. Warm, aerated spa water can also support other pathogens such as Pseudomonas aeruginosa (associated with folliculitis / "hot tub rash") and gastrointestinal organisms from inadequately treated water; service engineers should be aware of these risks even where they fall under different regulatory frameworks.

Who Does HSG282 Apply To?

HSG282 applies to anyone responsible for managing or operating spa-pool systems in a commercial or business context. That includes:

Leisure centres and health clubs with Jacuzzis or hydrotherapy pools
Hotels with spa pools in guest rooms or common areas
Holiday parks where rental units include hot tubs
Glamping sites with guest hot tubs
Beauty salons and wellbeing centres with foot spa equipment
Any business providing access to a spa pool, whirlpool bath, or aerated warm water system to customers or guests

Importantly, the guidance explicitly covers "domestic-type spa pools or hot tubs used as part of a business activity" — so a holiday let with a hot tub in the garden is within scope if the property is let commercially.

Private residential hot tubs used solely by the owner's household are outside HSG282's scope (there is no business duty), but the same physical risks exist and the same treatment approaches apply.

Why Spa Pools Are Higher Risk Than Swimming Pools

Two physical factors make spa pools significantly higher risk than swimming pools from a Legionella perspective:

Temperature. Legionella multiplies rapidly between 20°C and 45°C, with optimal growth around 37°C. Spa pools and hot tubs operate at 36–40°C — precisely this range. Swimming pools, at 26–28°C, are below the optimal Legionella growth band. This is why the disinfectant demands and testing frequencies for spa pools are much more stringent.

Aerosolisation. Spa jets and air injection systems create fine water aerosols that bathers inhale directly. Legionella is not waterborne in the ingestion sense — it is inhaled as an aerosol. A spa pool with active jets is an efficient aerosol generator, which is exactly why an inadequately treated spa pool can cause a Legionnaires' disease outbreak from a relatively small number of bathers.

HSG282 Core Requirements

Written Scheme of Treatment (Schematic / Operational Manual)

Every commercial spa pool must have a written scheme of treatment. This is a documented operational procedure covering:

Water treatment chemicals and target ranges
Dosing method (manual or automated)
Testing frequency and who carries it out
Action thresholds (what happens if readings are out of range)
Cleaning and disinfection schedule
Drain-down and refill frequency
Record-keeping system

For holiday park or hotel hot tubs where a pool service engineer manages the water treatment, the written scheme is typically developed with or by the engineer and reviewed annually. It is not a one-page checklist — it is a living operational document. If a local authority inspector or environmental health officer investigates a Legionella incident, the written scheme is one of the first items requested.

Water Treatment Targets

The chemistry demands for spa pools are more stringent than swimming pools because of the higher temperature, lower water volume (which means contamination has a larger proportional impact), and aerosol risk.

Disinfectant: PWTAG guidance for spa pools specifies free chlorine at 3.0–5.0 mg/L (higher than the residuals PWTAG sets for hypochlorite-dosed swimming pools, where its operative aim is 0.5–1.0 mg/L with a 3.0 mg/L upper limit; 1.0–3.0 mg/L is the wider general working band commonly quoted). Bromine is also approved at 4.0–6.0 mg/L free bromine — many operators prefer bromine for spa pools because it remains effective at higher pH levels and higher temperatures.

Combined chlorine / combined bromine: PWTAG's Code of Practice combined-chlorine rule is that it "should always be less than half the free chlorine, and no more than 1mg/l." For spa pools operators commonly work to a tighter figure — around 0.2 mg/L combined chlorine — because combined chloramine compounds are volatile at spa pool temperatures and are directly inhaled by bathers via the aerosol. This tighter spa-specific target is industry practice / HSG282-related guidance rather than a number stated in PWTAG's main Code of Practice rule. Even a slight elevation is significant.

pH: PWTAG recommends pH be maintained between 7.2 and 7.4 (the same range applies to swimming pools), but holding pH in this range is more challenging in spa pools because bather load is high relative to water volume, and jet aeration raises CO₂ outgassing which shifts pH upward.

Temperature: Spa pools are typically operated at 36–40°C. Operating above 40°C is not recommended — UK guidance reflects this because temperatures above 40°C increase Legionella risk further, can cause hyperthermia in bathers, and degrade chlorine effectiveness more rapidly.

Testing Frequency

The testing frequency requirements for commercial spa pools are more demanding than for swimming pools. Per HSG282 and PWTAG guidance:

Free chlorine and pH: minimum every hour during operation
Combined chlorine/bromine: at least daily during operation
Total dissolved solids (TDS): at least monthly (TDS builds in spa pools due to high chemical dosing and low dilution ratio)
Turbidity (water clarity): at each operational test

Most commercial spa pools require automated dosing and automated monitoring rather than purely manual hourly tests. If you're maintaining a hotel or holiday park spa pool that relies on the duty manager doing hourly manual tests, that's a practical compliance gap that automated dosing/monitoring resolves.

Drain-Down and Refill

Because spa pools have a low water volume relative to bather load, and because TDS builds up from chemical dosing, HSG282 guidance requires periodic complete drain-down and refill. The frequency depends on bather load and TDS readings:

Minimum: at least every 3 months for low-use spa pools
More frequent: high-use spa pools (hotel pools with multiple bathers per day, leisure centre whirlpool spas) may need monthly or more frequent refills
Trigger-based: if TDS exceeds threshold values or water quality can no longer be maintained within targets, drain down regardless of schedule

During drain-down, the physical cleaning of the spa shell, pipework (line flushing), filter clean, and any UV chamber servicing should all be completed before refilling.

Cleaning and Disinfection

The pipework of spa pools is a major Legionella risk area — biofilm accumulates in the dead legs and low-flow sections of the circulation system. Regular cleaning includes:

Pipework flush: at each drain-down, use a proprietary line-flush product at elevated concentration to break down biofilm in the spa pipework before draining
Shell clean: physical scrub of the spa shell and seating surfaces
Filter inspection and clean: cartridge filters should be cleaned at regular intervals (check manufacturer guidance — many spa pools use cartridge filters that require manual cleaning every 2–4 weeks under high bather load)
UV lamp inspection: if a UV system is fitted, inspect the quartz sleeve and record the lamp hours at each drain-down

Record-Keeping

Record-keeping for HSG282 compliance must cover:

Every water test result (date, time, tester, FC/bromine, CC, pH, temperature, TDS)
Chemical additions (date, time, product, quantity)
Cleaning activities (date, scope, who carried out)
Drain-down and refill dates
Filter cleaning dates
UV lamp replacement dates
Any bather incidents or complaints of skin/respiratory symptoms
Annual written scheme review

For commercial spa pools with regular service engineer visits, the engineer's visit report becomes part of this record. Some local authority licensing regimes (particularly for leisure centres) will audit these records annually.

The Interaction with L8 ACOP

HSG282 sits alongside the Approved Code of Practice for the Control of Legionella Bacteria in Water Systems (L8 ACOP). The L8 ACOP is the legal anchor — compliance with L8 (as an ACOP, it gives presumption of compliance with the Health and Safety at Work Act) and HSG282 provides the specific technical application of that framework to spa pool systems.

Practically, this means that spa pools are subject to two overlapping frameworks:

General Legionella risk management under L8 ACOP — risk assessment, written scheme, responsible person, monitoring, and records
Spa-pool-specific operational requirements under HSG282 — the technical parameters, testing frequencies, and drain-down/cleaning schedules specific to these systems

Larger leisure operators (hotel groups, leisure trusts) typically have a Legionella risk assessment covering all water systems on the premises (cooling towers, hot water services, showers, spa pools) under L8. The spa pools within that estate have an HSG282 regime as their specific treatment protocol.

Practical Implications for Service Engineers

If you service spa pools commercially, HSG282 has practical implications for every visit:

Document everything. Every test result, every chemical addition, and every maintenance action needs a record. If a guest develops Legionnaires' disease after staying in a property you service, your records are the primary evidence that you met your contractual duty of care (and your client met theirs).

Act on out-of-range readings immediately. An out-of-range FC or pH reading on a spa pool is a higher-risk situation than on a swimming pool. Do not leave a spa pool with low disinfectant and assume it will be corrected at the next visit. If you cannot correct it on-site, the spa pool should be closed to bathers.

Know the drain-down schedule. Ensure you and your client have an agreed drain-down and refill schedule documented in the written scheme, and that you're tracking TDS to know if an unscheduled drain-down is needed.

Legionella symptoms to flag to clients: advise clients to record any bather complaints of respiratory illness, unexplained fever, or muscle aches within 2–10 days of spa pool use. These may be the early signs of Legionnaires' disease. If a cluster of cases is identified, the local environmental health team must be notified.

Higher-risk clients: elderly guests, guests with chronic respiratory or immune conditions, pregnant women, and smokers are at higher risk of severe Legionnaires' disease. Leisure properties catering to these demographics (convalescent hotels, retirement parks) should have robust HSG282 compliance as a non-negotiable contractual term.

See our swimming pool risk assessment guide for how risk assessment works in the broader pool safety framework, or our pool plant operator course guide for how HSG282 is covered in UK pool plant qualifications.

PoolRound is building water chemistry logging and visit records for UK pool and hot tub service engineers — including the testing frequency and chemical addition records that HSG282 compliance requires. Join the waitlist for early access.

This guide reflects HSG282 and PWTAG guidance as understood at the date of last review. HSG282 was last updated in 2017/2018; always check hse.gov.uk for the current version. Spa pool operation involves biological hazards with serious public health implications — always follow the current guidance, maintain the records required, and seek expert advice when in doubt. Not professional safety, legal, or regulatory advice.

Sources

HSE HSG282: Control of legionella and other infectious agents in spa-pool systems — primary guidance for spa pool operators and engineers
HSE L8 ACOP: Legionella bacteria in water systems — Approved Code of Practice, the legal framework for Legionella risk management
HSE HSG179: Managing health and safety in swimming pools — companion guidance for swimming pools (4th edition, updated February 2024)
PWTAG Code of Practice — water quality targets for spa pools and swimming pools